<?php
//heredoc 相当于双引号
$word = 'hello';
$s = <<<TEST
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<h1>{$word}frank</h1>
</body>
</html>
TEST;

echo $s;
